Optical nonlinearity of glass containing nanoparticle CdS and SnO_{2:Eu³⁺

The sol-gel method was applied to the preparation of glasses doped with nano-sized CdS and SnO2 particles of 5–10nm in diameter. Band gap energies of the nano-sized particles exhibited large blue shift compared with those of bulk crystals and the energy shift was reciprocally proportional to the square of the particle size. The third order nonlinearity of the nano-sized CdS particles showed the maximum value of 1.5610-10 esu at the optical absorption edge position. The Eu³+ ions were doped in the nano-sized CdS and SnO2 particles-precipitated glasses, of which the fluorescence intensities were enhanced by the existence of the nano-sized particles. The energy absorbed by the quantum-dot effect in the nano-sized particles is efficiently transferred into the Eu³+ ions to cause the high emission. Particularly, the Eu³+ ions doped in nano-sized SnO2-containing glasses exhibited the enhanced fluorescence of the 5D0→7Fj transitions. When excited at the energy corresponding to the absorption edge of the SnO2 nanocrystals, the fluorescence intensities of the Eu³+ ions were enhanced up to 150 times higher than the glass without nanocrystals.